Risk factors for the acute leukemias in adults continue to be explored in a case-control study in which patients can be classified according to clonal chromosome characteristics, immunologic phenotype, and other biochemical markers. A total of 658 acute leukemia patients who were enrolled in cancer treatment protocols sponsored by Cancer and Leukemia group B, a cooperative cancer study group, and 637 population controls were interviewed regarding exposure to solvents and chemicals, smoking, irradiation, use of potentially toxic medications, and family medical history. An additional 250 AML patients and 125 myelodysplasia patients were also interviewed for related studies. Early results indicate increased risk associated with smoking and residence near factories as well as an association between occupational exposure to solvents and ras gene activation in AML. Laboratory assessment of ras gene activation has been completed for approximately 100 of 250 additional AML patients being studied in hopes of confirming the association between ras and chemical exposure. Recent results confirm an association between hair dye use and risk of both AML and ALL. Use of any hair dyes was associated with about a fifty percent increase in leukemia risk, with the greatest risk associated with use of permanent dyes. Risk also increased with years of use and was greatest for those who began using dyes at an early age. Employment as a beautician or cosmetologist was associated with a 3-fold increase in leukemia risk and was associated with loss of chromosome 7, a clonal chromosome abnormality that has been reported in association with exposure to solvents and chemotherapeutic agents. Efforts have also focused on preparing occupational and chemical exposure data for analysis. Preliminary results suggest an association between occupational exposure to solvents and radiation and risk for specific chromosome abnormalities in AML and ALL, including loss of chromosome 7 and the Philadelphia chromosome. Current analyses are focusing on vitamin supplements and potentially decreased risk for specific leukemia subtypes and on possible risk factors for myelodysplasia.